Bulletin of the American Physical Society
60th Gaseous Electronics Conference
Volume 52, Number 9
Tuesday–Friday, October 2–5, 2007; Arlington, Virginia
Session WF1: Biological and Emerging Applications of Plasmas |
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Chair: Scott Walton, Naval Research Laboratory Room: Doubletree Crystal City Crystal Ballroom A |
Friday, October 5, 2007 10:30AM - 11:00AM |
WF1.00001: Low-energy electron interactions with hydrated DNA and complex biological targets Invited Speaker: We have theoretically and experimentally examined low-energy (5-50 eV) electron induced damage of hydrated DNA targets. In particular, we have modified a multiple scattering ``path approach'' to theoretically calculate low-energy (5-50 eV) electron diffraction and incident electron intensity at particular sites within a hydrated DNA double-strand. Constructive interference associated with water in the DNA major grooves occurs and can enhance the experimentally observed DNA damage probability. We associate the observed enhancements in the break probability as a function of incident electron energy with diffraction and decay of compound core-excited Feshbach resonances. These excitations are localized at the hydrated DNA interface but can decay by autoionization and lead to damage at sites spatially removed from the initial excitation. Diffraction can enhance damage but the inherent spatial specificity is not preserved. We have also begun studies to examine spatially and chemically resolved plasma mediated desorption of small molecules from complex targets such as cell membranes. [Preview Abstract] |
Friday, October 5, 2007 11:00AM - 11:15AM |
WF1.00002: Nanostructured heterolayers for biosensor and photovoltaic nanodevices: A plasma technique Amanda Rider, Igor Levchenko, Kostya (Ken) Ostrikov Novel structures incorporating heterolayers of buried quantum dots (QDs) have been proposed for biosensors and solar cells, in some cases there is an additional layer of unburied, surface QDs or larger nanostructured islands, the signal from which is reported to be enhanced due to correlation with the buried QDs. Such devices are particularly alluring due to the current research focus on nanobiotechnology and renewable energy. For satisfactory device performance, care must be taken to ensure a high level of control over the composition, size, morphology and positioning of these QDs, both buried and on the surface. Such considerations are crucial for, amongst other things, band-gap engineering efforts, device efficiency and bio-functionalization. The distinct advantages of the low-temperature growth afforded by plasmas are particularly notable when considering biological and photovoltaic applications. The utilization of plasma-based methods is a promising way to ensure all these requirements are met. We demonstrate through hybrid numerical simulation, the plasma-assisted fabrication of both buried and surface quantum dots with precise control over composition [1], size-uniformity [2], morphology, crystallinity and positioning. [1] A. E. Rider, J. Appl. Phys. 101, 044306 (2007); [2] A. E. Rider et al, Plasma. Process. Polym., article accepted (2007). [Preview Abstract] |
Friday, October 5, 2007 11:15AM - 11:30AM |
WF1.00003: Molded Microcavity Plasma Arrays And Channnels In Polymer Structures: UV Lighting Sources For Biophotonic Applications J. Zheng, T.S. Anderson, J.H. Ma, M. Lu, B.T. Cunningham, S.-J. Park, J.G. Eden Arrays of microcavity plasma devices, transparent in the ultraviolet(UV) have been fabricated in multilayer polymer structures by replica molding process. Microscale, on-chip UV-emitting light sources integrated into plastic substrate are an attractive tool for biomedical diagnostics such as cell detection or radiation treatments. In this presentation, arrays of microchannels with cross-sectional dimensions as small as 100 $\times $ 100 $\mu $m$^{2}$ and lengths up to 2 inches (aspect ratio of 500:1) are described. Each channel is hermetically sealed and contains mixtures of UV emitting gas such as Ar/N$_{2}$, Ar/D$_{2}$, and Ar/H$_{2}$O at atmospheric pressures. Channels are fabricated adjacent to one or more microfluidic channels containing a liquid dye solution which is photoexcited by the microplasma. Driven by an ac voltage source, the microchannel plasmas are observed to be stable glows and the microplasma emission is found to be dependent upon the electrode geometry. The characteristics of the UV emission produced by the microplasmas, and the selective detection of dye samples in the fluidic channel will be discussed. [Preview Abstract] |
Friday, October 5, 2007 11:30AM - 12:00PM |
WF1.00004: Cold plasma treatment in wound care: efficacy and risk assessment Invited Speaker: Cold atmospheric plasma is an ideal medium for non-destructive modification of vulnerable surfaces. One of the most promising medical applications of cold plasma treatment is wound healing. Potential advantages in wound healing have been demonstrated in vitro: the plasma does not necrotize the cells and does not affect the extracellular matrix [1], has clear bactericidal or bacteriostatic effects [2], and stimulates fibroblast cells towards faster attachment and proliferation [3]. However, safety issues, such as the potential cytotoxicity of the plasma must be clarified prior to clinical implementation. This work comprises the recent facts on sub-lethal plasma effects on mammalian cells, as well as studies on apoptosis induction and quantitative assessment of DNA damage. Fibroblast, smooth muscle and endothelial cells were treated using the standard cold plasma needle [1,2]; intra- and extracellular oxidant levels as well as the influence of the plasma on intracellular antioxidant balance were monitored using appropriate fluorescent markers [1]. We have studied long-term cellular damage was monitored using flow cytometry to determine the DNA profiles in treated cells. Dose-response curves were obtained: increased proliferation as well as apoptosis were visualized under different treatment conditions. The results from the in vitro studies are satisfying. \newline \newline [1] I.E. Kieft, ``Plasma needle: exploring biomedical applications of non-thermal plasmas'', PhD Thesis, Eindhoven University of Technology (2005). \newline [2] R.E.J. Sladek, ``Plasma needle: non-thermal atmospheric plasmas in dentistry'' PhD Thesis, Eindhoven University of Technology (2006). \newline [3] I.E. Kieft, D. Darios, A.J.M. Roks, E. Stoffels, IEEE Trans. Plasma Sci. 34(4), 2006, pp. 1331-1336. [Preview Abstract] |
Friday, October 5, 2007 12:00PM - 12:30PM |
WF1.00005: Modeling atmospheric pressure plasmas for biomedical applications Invited Speaker: The use of cold, atmospheric pressure plasmas for biomedical treatments is an exciting new application in gaseous electronics. Investigations to date include various tissue treatments and surgery, bacterial destruction, and the promotion of wound healing, among others. In this talk, I will present results from modeling the `plasma needle,' an atmospheric pressure plasma configuration that has been explored by several groups around the world. The biomedical efficacy of the plasma needle has been demonstrated but the mechanisms of cell and tissue modification or bacterial destruction are only just being established. One motivation for developing models is to help interpret experiments and evaluate postulated mechanisms. The model reveals important elements of the plasma needle sustaining mechanisms and operating modes. However, the extraordinary complexity of plasma-tissue interactions represents a long-term challenge for this burgeoning field. [Preview Abstract] |
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